Getting a diagnosis of Alzheimer's or another form of dementia can cause anxiety and depression, at least for a short time. But can mental distress increase the risk for developing dementia?
Scientists assessed that question by reviewing the medical records of more than 70,000 men and women living in the U.K. All were part of the Health Survey of England, a large and ongoing annual survey. All were free of dementia at the start of the study period, in 1994, and their average age was 55.
Study participants were giving annual health questionnaires that asked about problems like anxiety, depression, poor social functioning and loss of confidence. All are general measures of psychological health, and the higher the scores, the greater the likelihood of anxiety and depression.
By the end of the study period, 10 years later, more than 10,000 of the study participants had died from various causes. According to death reports, 455 had died with a diagnosis of Alzheimer's or other forms of dementia.
Those men and women with the highest mental distress scores were more likely to have died from dementia than those who were psychologically healthy. The link between psychological distress and death from dementia was independent of other factors that may raise dementia risk, including smoking, alcohol abuse, years of schooling or physical ailments like heart disease or diabetes.
"Cardiovascular risk factors have been linked with dementia, but the association found in our study remained after controlling for them, thus implicating other explanations for the gradient seen," the authors wrote.
One possibility, the researchers propose, is that chronic levels of psychological distress may raise levels of the stress hormone cortisol. Persistently high levels of cortisol, in turn, may have toxic effects on the hippocampus, a part of the brain that is critical for memory.
They call for further research to investigate whether appropriate treatment of depression reduces dementia risk. They also note that understanding the links between psychological distress and dementia is important, since treatments for depression and anxiety are available and effective.
Tom C. Russ, Mark Hamer, Emmanuel Stramatakis, et al: "Psychological Distress as a Risk Factor for Dementia Death." Archives of Internal Medicine, Vol. 171. No. 20, Nov. 14, 2011.